Tuning Solid-State Fluorescence of a Twisted π-Conjugated Molecule by Regulating the Arrangement of Anthracene Fluorophores

Abstract

1-(5-(Anthracen-9-yl)-3-(4-methoxyphenyl)-4,5-dihydropyrazol-1-yl)ethanone was synthesized and crystallized to provide three types of crystals with different fluorescent colors and host−guest structures. Crystal structure analysis reveals that this compound possesses twisted π-conjugated structure and different degrees of distortion depending on guest molecules in the three crystal structures. The anthracene fluorophore stacking modes are regulated from monomer arrangement to face-to-face πstacked arrangement by means of the entrapment of organic acid molecules in the lattice. The vibrational spectroscopy, thermal behaviors, diffuse reflectance absorption spectroscopy, solid-state fluorescence properties, and fluorescence quantum yields and lifetimes of the three types of crystals were investigated. Such properties are closely related to the fluorophore stacking modes and intermolecular electronic interactions in crystals. The π-stacked geometries of anthracene fluorophores are responsible for the red-shifted emissions and longer fluorescence lifetimes. It indicates that the optical properties of organic materials could be modulated by entrapping different guest molecules in lattice.

Exploration of the Luminescence Properties of Organic Phosphate Salts of 3‐Quinoline‐ and 5‐Isoquinolineboronic Acid

“…The 2D fingerprint plot illustration allows identifying the contributions of the different types of non‐covalent interactions . The O‐H ··· – O/O and N + –H ··· – O/O interactions for each of the salts are represented by well‐defined elongated pegs marked with labels a and b ; meanwhile, the more disperse zones in blue color correspond mainly to C‐H ··· O contacts (Figure ).…”

“…In the fluorescence spectra, all salts exhibit mirror images of the corresponding excitation spectra, which is attributed to transitions from the lowest vibrational level of the first excited singlet electronic state (S 1 ) to the vibrational levels of the singlet ground state (S 0 ). [14b], The Stokes shifts for 3QBA‐1NP , 5IQBA‐1NP and 3QBA‐DPP with values of 140, 104 and 61 nm, respectively, are indicative of charge transfer, which might be associated to the S 0 →S 1 transition. Interestingly, the emission spectra of the compounds are significantly different from those of the individual molecular components (Figure S10–S12, ESI), evidencing that the proton transfer from the phosphate to the boronic acid and the changes in the supramolecular organization play a significant role for the optoelectronic properties ,.…”

Resonance Energy Transfer Emission Observed in Cocrystal of N,N′-Bis(3-imidazol-1-ylpropyl)naphthalenediimide with Cinnamic Acid

“…This is reflected in very weak emission at 561 nm originating from the opposing effect of resonance energy transfer due to quenching by stacking. Earlier, it was shown that arrangements of naphthalimide or other fluorophores influence fluorescence emission. This study clearly delineates that arrangements of nap ‐rings alone or together with rings of conformer molecules in cocrystal or salt are responsible for tuning the fluorescence emissions.…”

Understanding charge transfer stacking mode in cocrystals involving Tetrachloro‐p‐benzoquinone via experimental (SXRD, DSC‐TGA, DRS) studies and hirshfeld surfaces analysis

“…1‐acetyl‐3‐phenyl‐5‐(1‐pyrenyl)‐pyrazoline (APPP), 1‐(5‐(anthracen‐9‐yl)‐3‐(4‐methoxyphen‐yl)‐4, 5‐dihydropyrazol‐1‐yl) ethanone (AMPE) and PPPO were synthesized according to the procedure previously reported in our laboratory . Tetrachloro‐p‐benzoquinone (TCQ, CAS 118‐75‐2) was purchased from Alfa and used without further purification.…”